5-hydroxy-1, 3, 4-triazaindolizines as stabiliziers for photographic silver-halide emulsions



Patented Sept. 28, 1948 S-HYDROXY 1,3,4 TRKAZAINDGLIZINES AS STABILIZERS FR PHTOGRAPHIC SL- VER-HALIDE EMULSINS Newton Heimbach, Binghamton, N. Y., assigner to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware Application October 22, 1946, Serial No. 704,932

12 Claims. (Cl. 95--7) This invention relates to -hydroxy-lfl-triazaindolizines, and particularly to photographic silver-halide emulsions containing the same.

It is known in the art that light-sensitive emulsions, such as gelatin silver-halide emulsions, have a decided tendency to fog. The fog may be of two types, namely, yellow fog and chemical (gray) fog. The yellow fog, sometimes referred to as color lfog or dichroic fog, is essentially a lcolloidal deposit of silver, the color intensity and general appearance of which are determined by the minute particle size and degree of subdivision. The fog is chiefly yellow in color and is most apparent in the lighter portions of a negative. The color may vary, however, and the colloidal silver particles may, for example, appear green by reflected light and yellow or red by transmitted light. The so-called chemical fog, or gray fog, on the other hand, is the more common and is formed in a number of ways. It may be caused by premature exposure, by excessive ripening of the emulsions, or by the storage of the lm, particularly at high temperatures or for unusually long periods of time.

It is an object of the present invention to provide -hydroxy-1,3,4-triazaindolizines as stabilizers for silver-halide emulsions.

A frurther object is to provide 5-hydroxy-1,3,/ltriazaindolizines as stabilizers or fog inhibiting agents which tend to prevent the formation of chemical fog in light-sensitive siliver-halide emulsions.

A still further object is to provide stabilizers or anti-fogging agents for light-sensitive silverhalide emulsions, which increase their stability without lowering their sensitivity.

Still further objects and advantages will appear from the following specication.

I have found that the above objects are accomplished by employing a product obtained by :condensing an alkoxymethylene malonic acid ester with a 3-amino-1,2,4-triazole. The product is characterized by a structure corresponding to the following general formula:

wherein R is hydrogen or a carbalkoxy group, e. g., carbomethoxy, carbethoxy, carbopropoxy,

RaOC=O C O ORS COOR5 wherein R3 and R5 are alkyl groups as referred to above in the definition oi R2, R4 in either hydrogen, methyl, or a phenyl group, with 1 mol of 3-amino-1,2,4triazole of the following general formula:

wherein Re is of the same value as R2.

Suitable alkoxymethylene malonic esters are, for example, methoxymethylene malonic acid dimethyl ester, methoxymethylene malonic acid diethyl ester, ethoxymethylene malonic acid dimethyl ester, ethoxymethylene malonic acid diethyl ester, ethoxyphenylmethylene malonic acid diethyl ester, ethoxymethylene malonic acid dipropyl ester, methoxymethylmethylene malonic Aacid dimethyl ester and the like.

As suitable 3-amino-1,2,4-triazoles may be mentioned, 3-amino-1,2,4triazole, 3-amino-5- methyl 1,2,4 triazole, 3-amino-5-ethyl-l,2,4 triazole, 3-amino-5-propyl-1,2,4-triazole, S-amino-5-butyl-l,2,4-triazole, S-amino 5 phenyl- 1,2fl-triazole, -amino--carboxy-1,2,fl-triazole, S-amino 5 icarbethoxy-1,2,4-triazole, and the like.

The condensation between the alkoxymethylene malonic acid ester and the 3-amino-1,2,4triazole is carried out by heating the reaction components at a temperature ranging from to 120 C., preferably at reflux temperature, in the presence of an inert, water-binding, solvent diluent, such as glacial acetic acid, and the like for a period of l to 3 hours. During this treatment 2 molecules of alcohol are formed as the condensation or ring closure between the reactants proceeds.

3 The nal product either precipitates or is removed by diluting the solvent-diluent with water, ethyl ether, acetone, or the like, and is recrystallized from alcohol, e. g. methanol, ethanol, etc., or an alcohol-water mixture.

The carbalkoxy groupI in the -position (R group) of the -hydroxy-1,3,4-triazaindolizines may be replaced by hydrogen by saponii'lcation and decarboxylation of said carbalkoxy radical. This saponication and decarboxylation are accomplished by heating the compound, containing the carbalkoxy radical, at a temperature ranging from 90 to 110 C., or at reflux temperature, in the presence of a 5% aqueous solution of a water soluble alkali, such as sodium carbonate, sodium or potassium hydroxide, and the like, for a Iperiod of 1/2 to 1 hour. The reaction mixture is cooled, diluted with water and ltered. There is then added thereto an excess of 5 N H2SO4. The mixture is next boiled for 1/2 hour and cooled. A few cc. of 5 N NaOH are added to neutralize the excess H2504 and the solution allowed to stand in an ice bath for about 1 hour, during which time the decarboxylated compound precipitates. The final product is recrystallized from boiling Water.

The 3amino1,2,4triazoles and the alkoxymethylene malonic' acid esters are well-known to the art and the methods for their preparation need not be described herein.

Specific compounds which have been prepared in accordance with the above procedures, With their formulas, are as follows:

(l) CH HO N 5-hyd1 oxy-6-carbethoXy-1,3,4-triazaindolizine HO-C HaCOOC-C 5-hydroxy-6-carbomethoxy1,3,4-ttiazaindolizine a Hao o o c-c HO-C N processes of purification may be resorted to wherever found desirable. These and other Variations and modifications will be evident to those skilled in the art in light of the principles disclosed herein.

Example I Je H5020 O C-C N-N A solution of 0.25 Inol (54 grams) of ethyl eth oxymethylene malonate and 0.25 mol (21 grams) of 3amino1,2,4triazole in 40 cc. of glacial acetic acid was reuxed for two to three hours. Upon cooling, a white product precipitated. After filtering and washing, the compound was recrystallized from 50% methanol,

Eample II HO-C C=N 5-hydroxy-l,3,4-triazaindolizine 2 grams of 5-hydroxy-6-carbethoxy-1,3,4tri azaindolizine, prepared according to Example I, Was warmed on the steam bath with cc. of 5% NaOI-I solution for 1/2 hour. The solution was cooled, diluted `with 50 ce. of water and filtered. To the ltrate were added 7 cc. of 5 N I-IzSO'i. The mixture was then boiled for 1/2 hour and cooled. 2 cc. of 5 N NaOH were added and the solution was allowed to stand in an ice bath for one hour, during which time the decarboxylated compound precipitated. The product was recrystallized from boiling water.

Example III e@ HO-C O=N N 5-hydroxy-6-carbethoxy2phenyll,3,4-triazaindolizine Example I was repeated with the exception that an equivalent quantity of 3amino5phenyl 1,2,4-triazole was substituted for 3-amino-1,2,4- triazole.

In the preparation of an emulsion containing the stabilizers used according to my invention, a solution of the stabilizer in a suitable solvent, such as alcohol or an alcohol-water mixture, adjusted to a neutral or slightly alkaline pH, i. e., pH 7.5 to 10, is made up and the solution mixed with the emulsion at any point during its preparation, but preferably during ripening or just prior to coating in concentrations varying from mg. to 500 mg. per liter of emulsion. The actual concentration employed will depend upon the type of emulsion used and varies slightly with the -compound employed.

The method of testing the stabilizers'in the following examples consists of coating two lm strips, such as cellul-ose acetate, with the same emulsion, one with and one without stabilizer, storing the emulsions in an incubator for six days at 50 C., then exposing, developing, lxing, and washing the same under standard conditions. The fog density or blackening produced in the unexposed areas in the two emulsions is then measured in a transmission densitometer of standard type.

The following examples will serve to illustrate certain ways in which the stabilizers of my invention have been applied, but are not to be construed as limiting the invention.

Eample IV conditions, after incubation for six days at 50 C.,

gave a fog of 0.28 density. Another lm, coated with the same emulsion containing an addition of mg. of the compound of Example I per 1000 cc. of emulsion equivalent to about 50 grams of silver nitrate and developed under the same conditions, after the same incubation, gave a fog of 0.08 density.

Example V Example IV was repeated with the exception that an equivalent quantity of the compound of Example II was substituted for the compound of Example I. The results obtained were almost identical with those obtained in Example IV.

Example VI Example IV was again repeated with the exception that an equivalent quantity of the compound of Example 'III was substituted for the compound of Example I. After incubation and development, the emulsion containing the compound of Example III gave a fog of 0.1.

Further experiments have shown that emulsions containing stabilizers in accordance with my invention have not only improved keeping qualities (i. e., a reduction in the fog produced by incubation or by long storage) but undergo little or no change in speed to which some emulsions are susceptible.

The stabilizers, which I have described and employed, may be used in various kinds of emulsions. In addition to being useful in orthochromatic and panchromatic emulsions, they may also be used in non-sensitized emulsions and X-ray emulsions. If used with sensitizing dyes they may be added to the emulsion before or after the dyes are added. The dispersing agents for the silver-halides may be gelatin or other colloid such as, Water-soluble cellulose derivatives, e. g., hydroxy ethyl cellulose, methyl cellulose, carboxy-oxy-cellulose, low acetyl value cellulose acetate, polyvinyl alcohol, and the like. The stabilizers may also be employed in gelatin or other colloid, such as polyamides or a mixture of gelatin with a polyamide as described in United States Patent 2,289,775; polyvinyl alcohol and jelling compound as described in United States Patent 2,249,537; polyvinyl acetaldehyde acetal resins and partially hydrolyzed acetate resins described in United States Patents 1,939,422 and 2,036,092; cellulose derivatives, e. g., cellulose nitrate, cellulose acetate, the lower fatty acid esters of cellulose including simple and mixed esters, ethers of cellulose, and the like, as an under or overcoat for the emulsion, or as a backing layer for the support. Moreover, they may be incorporated in the support for the sensitive emulsion layer or in an intermediate layer between the sensitive emulsion layer and the support, such as the baryta coating commonly used in photographic papers, or they may be incorporated in a protective layer coated upon the emulsion surface. Furthermore, the otherwise finished photographic material may be bathed in an alcohol or alcohol-water solution containing the stabilizer.

In the accompanying drawing the various gures are enlarged section views of photographic materials having anti-fogging layers made according to my invention.

As shown in Figure 1, the support l, which may be of any suitable material such as glass, cellulose ester, synthetic resin, or paper, is provided with an anti-fogging layer 3, containing one of the 5 hydroxy 1,3,4 triazaindolizines referred to above, The light-sensitive emulsion layer 2 is attached to the anti-logging layer 3.

Figure 2 illustrates a similar material in which the support l is coated with a light-sensitive emulsion layer 2, and onv the latter side thereis provided an anti-fogging layer 3 containing one of said -hydroxy-1,3,4-triazaindolizines.

Figure 3 illustrates a lm or plate of which the support I bears on one side the light-sensitive emulsion layer 2, and on the other side an antifogging layer 3 containing such -hydroXy-lfltriazaindolizines.

Figure 4 illustrates a lm, plate, or paper of which the support I is provided with the lightsensitive emulsion layer 2 containing as an antiogging layer such 5-hydroXy-1,3,4-triazaindolizines.

Since the presence of these new compounds tends to prevent chemical fog whether they are incorporated directly into the emulsion, added to a separate surface or substratum layer, it is understood that the term photographic material as employed herein and in the appended claims, is used in a generic sense to include each of these possible applications.

Various modifications of this invention will occur to persons skilled in the art, and it is, therefore, understood that the patent granted shall only be limited by the appended claims.

I claim:

1. A photographic material comprising a base and a light-sensitive silver-halide emulsion carried thereby, said photographic material containing, in fog inhibiting amount, a compound of the general formula:

H3C O O C-C 3. A photographic material comprising a base and a light-sensitive silver-halide emulsion carried thereby, said photographic material containing, in fog inhibiting amount, a compound of the formula:

4. A photographic material comprising a base and a light-sensitive silver-halide emulsion carried thereby, said photographic material containing, in fog inhibiting amount, a compound of the formula:

Ho-o\\ /cz 5. A photographic material comprising a base and a light-sensitive silver-halide emulsion containing, in fog inhibiting amount, a compound of the general formula:

'7. A photographic material comprising a base and a light-sensitive silver-halide emulsion containing, in fog inhibiting amount, a compound of the formula:

8. A photographic material comprising a base and a light-sensitive silver-halide emulsion containing, in fog inhibiting amount, a compound of the formula:

H5020 O C-O 9. A photographic gelatino silver-halide emulsion containing from about 25 mg. to about 500 mg. per liter of emulsion of a compound of the general formula:

wherein R is a member selected from the class consisting of hydrogen and carbalkoXy groups, R1

is a member selected from the class consisting of hydrogen, methyl and phenyl groups, and R2 is a member selected from the class consisting of hydrogen, alkyl, aryl, carboxy, and carbalkoxy groups.

10. A photographic gelatine silver-halide emulsion containing from about 25 mg. to about 500 mg. per liter of emulsion of a compound of the formula:

11. A photographic gelatino silver-halide emulsion containing from about 25 mg. to about 500 mg. per liter of emulsion of a compound of the formula:

10 12. A photographic gelatine silver-halide emulsion containing from about 25 mg. to about 500 mg. per liter of emulsion of a compound of the formula:

NEWTON HEIMBACH.

Name Date Heimbach Dec. 11, 1945 Number 

